After a high-ranking North Korean official requests asylum, KCIA Foreign Unit chief Park Pyong-ho and Domestic Unit chief Kim Jung-do are tasked with uncovering a North Korean spy, known as Donglim, who is deeply embedded within their agency. When the spy begins leaking top secret intel that could jeopardize national security, the two units are each assigned to investigate each other.

Rebellious Ki-soo from North Korea is mesmerized by tap dance in prison camps. Ki-soo joins as a team member of a dance team named 'Swing Kids'. Yet suddenly, their dreams about dancing in prison camps are put in danger.